I need to upload an image to NodeJS server to some directory. I am using connect-busboy node module for that.
I had the dataURL of the image that I converted to blob using the following code:
dataURLToBlob: function(dataURL) {
var BASE64_MARKER = ';base64,';
if (dataURL.indexOf(BASE64_MARKER) == -1) {
var parts = dataURL.split(',');
var contentType = parts[0].split(':')[1];
var raw = decodeURIComponent(parts[1]);
return new Blob([raw], {type: contentType});
}
var parts = dataURL.split(BASE64_MARKER);
var contentType = parts[0].split(':')[1];
var raw = window.atob(parts[1]);
var rawLength = raw.length;
var uInt8Array = new Uint8Array(rawLength);
for (var i = 0; i < rawLength; ++i) {
uInt8Array[i] = raw.charCodeAt(i);
}
return new Blob([uInt8Array], {type: contentType});
}
I need a way to convert the blob to a file to upload the image.
Could somebody help me with it?
This question is related to
javascript
node.js
file-upload
blob
The answer is
This function converts a Blob into a File and it works great for me.
Vanilla JavaScript
function blobToFile(theBlob, fileName){
//A Blob() is almost a File() - it's just missing the two properties below which we will add
theBlob.lastModifiedDate = new Date();
theBlob.name = fileName;
return theBlob;
}
TypeScript (with proper typings)
public blobToFile = (theBlob: Blob, fileName:string): File => {
var b: any = theBlob;
//A Blob() is almost a File() - it's just missing the two properties below which we will add
b.lastModifiedDate = new Date();
b.name = fileName;
//Cast to a File() type
return <File>theBlob;
}
Usage
var myBlob = new Blob();
//do stuff here to give the blob some data...
var myFile = blobToFile(myBlob, "my-image.png");
I have used FileSaver.js to save the blob as file.
This is the repo : https://github.com/eligrey/FileSaver.js/
Usage:
import { saveAs } from 'file-saver';
var blob = new Blob(["Hello, world!"], {type: "text/plain;charset=utf-8"});
saveAs(blob, "hello world.txt");
saveAs("https://httpbin.org/image", "image.jpg");
Joshua P Nixon's answer is correct but I had to set last modified date also. so here is the code.
var file = new File([blob], "file_name", {lastModified: 1534584790000});
1534584790000 is an unix timestamp for "GMT: Saturday, August 18, 2018 9:33:10 AM"
You can use the File constructor:
var file = new File([myBlob], "name");
As per the w3 specification this will append the bytes that the blob contains to the bytes for the new File object, and create the file with the specified name http://www.w3.org/TR/FileAPI/#dfn-file
Use saveAs on FileSaver.js github project.
FileSaver.js implements the saveAs() FileSaver interface in browsers that do not natively support it.
My modern variant:
function blob2file(blobData) {
const fd = new FormData();
fd.set('a', blobData);
return fd.get('a');
}
For me to work I had to explicitly provide the type although it is contained in the blob by doing so:
const file = new File([blob], 'untitled', { type: blob.type })
This problem was bugg me for hours. I was using Nextjs and trying to convert canvas to an image file.
I just use the other guy's solution but the created file was empty.
So if this is your problem you should mention the size property in the file object.
new File([Blob], `my_image${new Date()}.jpeg`, {
type: "image/jpeg",
lastModified: new Date(),
size: 2,
});
just add it, the value it's not important.
Typescript
public blobToFile = (theBlob: Blob, fileName:string): File => {
return new File([theBlob], fileName, { lastModified: new Date().getTime(), type: theBlob.type })
}
Javascript
function blobToFile(theBlob, fileName){
return new File([theBlob], fileName, { lastModified: new Date().getTime(), type: theBlob.type })
}
Output
File {name: "fileName", lastModified: 1597081051454, lastModifiedDate: Mon Aug 10 2020 19:37:31 GMT+0200 (Eastern European Standard Time), webkitRelativePath: "", size: 601887, …}
lastModified: 1597081051454
lastModifiedDate: Mon Aug 10 2020 19:37:31 GMT+0200 (Eastern European Standard Time) {}
name: "fileName"
size: 601887
type: "image/png"
webkitRelativePath: ""
__proto__: File
Source: Stackoverflow.com